Bioaccumulation of mercury in Haemulopsis elongatus and Pomadasys macracanthus from the SE Gulf of California: condition indexes and health risk assessment.

Mercury (Hg) was measured in the muscle, liver, and gonads of Haemulopsis elongatus and Pomadasys macracanthus from Mazatlán (SE Gulf of California) to determine the relationships of the hepatosomatic index (HSI) and gonadosomatic index (GSI) of fish with Hg concentrations in the corresponding tissues. Health risk to consumers was assessed by using the hazard quotient (HQ), considering the average rate of fish consumption in Mexico and Hg concentration in the edible tissue. In H. elongatus, the highest Hg levels were measured in the liver (3.748 µg g-1); in P. macracanthus, the highest Hg concentration was quantified in the muscle (0.574 µg g-1). In P. macracanthus, the HSI was negatively correlated with Hg concentration in the liver; in H. elongatus, there was also a negative relationship between Hg levels in gonads and the GSI. Mean HQ values in Haemulopsis elongatus (0.005) and Pomadasys macracanthus (0.002) were below the value (HQ ≥ 1) of concern. The significant reduction of HSI and GSI with Hg increase in the liver and gonads may suggest that Hg bioaccumulation in these fish shows adverse physiological effects. Though HQ values in both species were below the unit, i.e., the consumption of the muscle from this species does not represent a health risk, it is necessary to carry out surveys of fish consumption rates in coastal areas of Mexico to do a more precise health risk assessment associated to Hg intake.

²¹°Po, Cd and Pb distribution and biomagnification in the yellowfin tuna Thunnus albacares and skipjack tuna Katsuwonus pelamis from the Eastern Pacific.

We measured Cd and Pb in the muscle and stomach contents of Thunnus albacares and Katsuwonus pelamis to define the distribution of the elements in the tissues and their degrees of biomagnification. (210)Po was measured in the livers of both species and compared to the results of similar studies. The trophic position of the tuna species was determined by N isotope measurements. The average activity of (210)Po in the liver ranged from 119 to 157 (Bq kg(-1) wet weight) in K. pelamis and T. albacares. The trophic position of T. albacares (4.60) was higher than that of K. pelamis (3.94). The Cd content of the muscle increased significantly with the trophic position of the tuna. δ(13)C in T. albacares and K. pelamis varied, with values of 3.13 and 1.88‰, respectively. The δ(15)N values in yellowfin tuna were higher than in skipjack tuna. The trophic position of T. albacares (4.60 ± 0.67) was therefore more elevated than that of K. pelamis (3.94 ± 1.06). Pb was biomagnified in T. albacares (transfer factor=1.46).